Periodontal diseases are a major cause of tooth loss in persons over 35 years of age. These plaque-dependent dental infections could be effectively eliminated if we could prevent the disease-associated bacteria from adsorbing to an accumulating on the surfaces of teeth. However, the mechanisms by which periodontal disease-associated bacteria attach to and accumulate on teeth in microbial plaques must be understood if dental diseases are to be controlled in this manner. This proposed project is a continuation of an in-depth study on the mechanisms of adsorption of periodontal disease-associated bacteria to hydroxyapatite surfaces under conditions which mimic the in vivo situation. In addition, parameters, such as the physical-chemical conditions of the adsorption environment, which may influence microbial adsorption to solid surfaces, will be evaluated. Particular emphasis is being placed on identification, isolation and immunochemical characterization of cell surface structures which mediate adsorption of the microorganism to saliva-treated hydroxyapatite surfaces using biochemical and immunologic techniques. Receptor molecules shown to mediate adsorption of various periodontal disease-associated bacteria to the "in vitro tooth surface" will be tested in experimental animals for use as potential vaccines to eliminate or cotrol colonization by periodontal disease-associated bacteria. This approach will hopefully lead to the development of immunization protocols in humans to control the various periodontal diseases.